A few weeks ago, I was tidying up my portable hard drive and came across a few photographs that my brother took of a couple of Yellow Cururu Toads (Rhinella icterica) copulating. He'd found them during a trip to the countryside of Sao Paulo, Brazil, at the end of 2011 - towards the end of the species' breeding season.

The R. icterica is an endemic species that can be found in Brazil, eastern Paraguay and the northeastern part of Argentina. It is considered to be a large toad species with males ranging from 100 - 166 mm in length and females ranging from 135 - 190 mm. Due to its sexual dimorphism, it is easy to differentiate males and females of this species - males have a distinct yellow colouration whereas females tend to be a greyish/brownish colour with symmetrical dark spots on either side of their spinal cord.

Female Rhinella icterica | Credit: Caio Biasoli

Male Rhinella icterica | Credit: Caio Biasoli

Similarly to other large toad species such as the Cane Toad (Rhinella marina), the R. Icterica has prominent parotoid glands behind their eyes. These granular glands produce toxic secretions that look like a milky substance if you were to squeeze them. As these toads are not very agile, preferring a 'sit and wait' approach to predation, the toxin secreted is one of their only defence mechanisms. Given their size, it is not surprising to learn that they prey on pretty much anything they can swallow. Having said that, studies indicate that a large portion of their diet may be made up of beetles and ants (Sabagh, Carvalho-e-Silva and Rocha, 2012).

Interestingly, in Brazil, the term 'sapo-cururu' is applied commonly to big toads, mostly of the Rhinella genus. The word 'Cururu' is Old Tupi in origin and used colloquially in some regions to describe an ugly human male. There's also a popular children folklore song named 'sapo-cururu' that makes reference to the loud calls made by the males of the species during the breeding season.

The Conraua goliath is one of those species that most people with no interest in amphibians will have heard of because of its size. The 'biggest frog' factoid being an almost must for any pub quiz...or perhaps more realistically, for any pub quiz I would certainly enjoy.

I decided to write about it due to a dream. Yes, that's right, a dream. Not long ago I dreamt that I found a large C. goliath specimen in my garden and I was over the moon about it. I mean, a living and breathing Goliath Frog in my garden! In England! The downside of this dream was that in it, I was the only person able to see the frog. The dream version of my husband couldn't see it at all...oh, the frustration! The next day, I was telling my friend Steven Allain about my strange dream. Realistically, he's one of the only people in my day-to-day life who would truly appreciate the frustration that my dream-self was experiencing. We got talking about C. goliath and I then decided that I would write a post about it. Why not? If I believed in such things, I would say the dream was a sign and all that. So, here it is.

Most people will know that the C. goliath - commonly known as the Goliath Frog or Giant Slippery Frog - is the largest species of living frog on the planet. Records show that adults average at around 12 inches in length and 3 kg in weight. Curiously, although the adults of the species are carnivores, the tadpoles are herbivores. In fact, the C. goliath tadpole's early diet is rather restricted and made up mainly of the Diacraeia warmingii plant. Unfortunately, as the range of this plant is limited, the spread of the C. goliath in the wild is also restricted to parts of Equatorial Guinea and Cameroon. As adults, however, the C. goliath's size means that almost anything is a potential meal. A few sources indicate that a researcher has found evidence of bats in the contents of a captured C. goliath individual's stomach. However limited the evidence may be, it does suggest that these frogs are able to catch bats to begin with...considering that this species can leap up to 10 feet, catching bats becomes a somewhat more believable feat.

Vendor showing his available C. goliath collection for sale in Cameroon | Photograph taken from The African Gourmet's website

Unlike most frog species, the males are usually bigger than the females. This may help explain another unusual characteristic of the species - males do not possess nuptial pads. Nuptial pads in male frogs are used to facilitate the grasping of the female during mating. Another curiosity in their biology is that although they have an acute sense of hearing, they do not possess vocal cords. Therefore, they do not produce sounds during the mating season as many other species of frogs do. C. goliath males will instead create round pools of shallow water by riverbanks and wrestle each other for the right to mate.

Their short mating season ranges from July to August and females will lay hundreds of eggs. Unlike other frog species, these eggs will receive no protection from the parents and the surviving tadpoles will take between 85-95 days to metamorphose into frogs. They rarely breed in the wild and captive-breeding is unfortunately also rarely successful. Furthermore, the Goliath Frog's meat is part of the diet of many African tribes and considered a delicacy by local people. Combined with the hunt for wild individuals in order to meet the demand of the pet trade, you will not be surprised to hear that this species is listed as endangered.

If like me, you too like reading about this amazing frog, I have listed my main sources below. If you know of any other major projects aimed at the conservation of the Conraua goliath, do let me know! I'd love to hear from you.

If you are lucky enough to have ever witnessed a wild common toad hunting, you will understand what I mean when I say that they are pretty endearing creatures. They have an incredibly entertaining 'walking' style that never fails to make me laugh.

Towards the end of my trip to Slovenia, I encountered the most gorgeous common toad specimen. As I was not actively searching for this species, it was a really nice surprise - mostly because the encounter reminded me just how much I enjoy observing them.

The toad showed up in the garden of the place where we were staying. It had rained quite a lot during the day and by 8:30 that evening, the garden looked like a slug & snail fest. The toad was too busy hunting snails and slugs to realise that I had already spotted it and was close enough to pick it up without much effort... not that common toads are difficult to capture under normal circumstances but it makes for a nice tale.

Not long after I picked it up, the toad (understandably frightened) released water from its water bladder. This prompted my surprised (and slightly disgusted) husband to jump three feet away from me and say 'Oh no, it's peed on you'. This defense mechanism is fairly common and although it isn't exactly the same as actual urine, the 'peeing on you' seems like the easiest way to explain it.

Common Toad (Bufo bufo) found in Krizevci Slovenia

Underside colouration and markings of the same Common Toad (Bufo bufo) individual

You will notice in these two photographs (sorry for the bad quality!) that I am wearing gloves to handle the toad. Let me firstly clear things up - you CANNOT get warts from handling toads (yes, some people really do ask that question). The real reason I am wearing gloves is to protect the toad from any harmful chemicals I most likely had on my hands and NOT to protect myself. As I mentioned before, the encounter was a surprise and although you cannot see it in the photographs, I was pretty sunburnt. I knew that my hands were covered in body lotion and, as amphibians have permeable skin, in order to protect the little toad, I put on the first pair of gloves that I could find. Obviously, they weren't the best fit but they did the trick.

A curious fact about the common toad is that they can actually secret large amounts of a distasteful white substance from their skin when threatened - although this doesn't seem to affect some predators such as Grass Snakes. Their eggs and tadpoles are also thought to be distasteful - a fact that is believed to contribute to its successful survival rate when compared to other amphibian species. It is also likely to somewhat explain the wide range of locations in which the species can be found.

Common Toad (Bufo bufo) found in Krizevci, Slovenia | Photograph by Talita Bateman

Unfortunately, this species tends to be attacked by Flesh Flies (Lucilia bufonivora) - its latin name is certainly a clue! The fly lays its eggs on the toad's skin and once the eggs hatch, the little maggots will often enter the toad's body via its nose and eat the toad from within. Quite the image huh?!

On a lighter note, the good news is that this species is not very difficult to find. If you are in the UK, depending on where you live, you can even encounter it in your own garden! If you go looking for them, try and remember a couple of important things: 1) Common Toads are nocturnal! 2) Record your sightings!

Nature is full of creatures with amazing ways to defend themselves. Aside from loss and contamination of natural habitat, predation is one of the greatest causes of death in amphibians. In fact, studies show that the vast majority of frogs and toads will not survive long enough to produce offspring.

Whereas some frogs are famous for their poisonous skin and bright colours, others rely on less offensive methods to defend themselves. In this post I present you the glass frogs of the family Centrolenidae and the Cyaba Dwarf Frog (Eupemphix Nattereri).

Let's start with the Glass Frogs. They are so named because the skin on their bellies is transparent. Due to this characteristic, glass frogs are known to have been used for teaching purposes. Out of the three genera in this family - Centrolene, Cochranella and Hyalinobatrachium - frogs of the subfamily Hyalinobatrachium have the most 'see through' belly skin. It is believed that the transparent skin helps these frogs to camouflage with their background and trick predators.

The Cuyaba Dwarf Frog, however, relies on a completely different method. This frog has two black and white round markings on its lower back. When threatened, it fools any would-be predators by inflating its body, lowering its head and lifting its rear end to display the markings. The markings justify this frog's famous nick-name - The False-Eyed frog.

However, the markings are not just an intimidation display. Should the initial showing of the markings fail to deter a predator, glands within the markings produce a noxious secretion aimed at the predator's mouth.

As humans, we tend to anthropomorphise animals. An animal's level of 'cuteness' will often be directly linked to a standard we created for ourselves and are able to project onto other creatures. Frogs have never had an easy time in human history. Due to folklore and an old fantasy book - much like the snake - frogs are seen as evil creatures. However, some frogs find it harder to captivate humans than others. The Surinam Toad is one of them.

This amazing toad is an aquatic species and a master of camouflage. Found in swamps and slow-moving rivers in northern South America, it is able to camouflage itself among the dead leaves at the bottom of muddy waters. It feeds on small fish and small aquatic invertebrates.

However, the most extraordinary thing about the surinam toad is, in fact, how they give birth. In an extremely rough summary, the reproduction ritual involves the male and female swimming up to the surface of the water. The male holds onto the female from above and they turn upside down whilst performing a series of movements that fertilise the eggs. During this process, the male deposits the eggs onto the female's back with its feet. The skin on the female's back becomes spongy and envelops each egg. The eggs stay there from 3-4 months until fully formed toadlets break out of the mother's skin and swim away.

Yes. As I previously mentioned, they are pretty amazing. It is something else when you can say that the larval habitat of a species are the skin pockets in their mother's back. Granted it may not make for the most pleasing visual. However, considering humans managed to turn childbirth and periods into something 'disgusting', it is understandable (but regrettable) that the surinam toad is unlikely to ever make it to the 'top 10 cutest animals ever' list.

It is worth noting that many frog species have unusual reproductive methods. In his book 'Life in Cold Blood', David Attenborough describes the reproductive methods of the Marsupial Frog (Gastrotheca). The clue is in the name but if you'd like to know more, I'd highly recommend the above mentioned book.

If, like me, you are intrigued by the surinam toad, the below video shows the incredible moment when the fully formed toadlets break free of the mother's skin.